Abstract
Background and aims Probe-based confocal laser endomicroscopy (pCLE) is used to differentiate between
neoplastic and non-neoplastic colorectal polyps during colonoscopy. We aimed to assess
the accuracy of two endoscopists starting to use real-time pCLE for differentiation
of colorectal polyps and to determine the negative predictive value (NPV) for neoplasia
in polyps ≤ 5 mm.
Methods Patients undergoing colonoscopy in a tertiary hospital were included in this prospective
trial. After a training session, two colonoscopists assessed 50 polyps between August
2012 and April 2014. They sequentially used narrow-band imaging (NBI) and real-time
pCLE to differentiate non-adenomatous, adenomatous, and carcinomatous polyps during
colonoscopy. Histologic diagnosis by a gastrointestinal pathologist was the gold standard.
Results were compared to post-hoc pCLE by a panel of gastroenterologists and pathologists.
Results The accuracy of real-time pCLE was 76 %, compared to 73 % for NBI, and was not significantly
different between the first 50 cases (74 %) and the last 50 cases (78 %, P = 0.64). The accuracy in polyps > 5 mm was 87 % versus 59 % in polyps ≤ 5 mm (P = 0.04) and increased from 45 % (13/29) in poor quality images to 86 % (44/51) in
fair quality images and 95 % (19/20) in good quality images (P < 0.01). The post-hoc pCLE accuracy was 62 %. The NPV for polyps ≤ 5 mm was 58 %
for real-time pCLE and 54 % for post-hoc pCLE.
Conclusion Although a fair accuracy of real-time pCLE for differentiation of colorectal polyps
can be achieved within 50 cases, low NPV and difficulty in obtaining high-quality
pCLE images hamper implementation in routine clinical practice.